A growing number of electronic systems are being built into vehicles to provide advanced features such as electrically assisted steering, ABS and active suspension components. These systems communicate over serial buses, such as a Controller Area Network (CAN) bus and, more recently, a FlexRay system bus.
Automotive manufacturers perform durability testing of vehicles and vehicle components (test specimens) in the laboratory by replaying data, measured during track test drives with specially instrumented vehicles, using hydraulic actuators to apply the equivalent loads and accelerations to the test specimens under the control of sophisticated software and hardware.
In the past, this testing has been limited to the analogue signals that are generated by monitoring vehicle behaviour and conditions that affect that behaviour, such as loads and accelerations at various points on the vehicle. This has been adequate for conventional test specimens without active components. However, the behaviour of modern vehicles is also dependent on the control data on the serial buses. For example, during a test drive, an in-car computer may determine the need to give feedback to a driver that the vehicle is close to its traction limit, or sensors within the vehicle may determine the need to stiffen a particular strut. Control signals are sent via the CAN bus to dynamically control the relevant vehicle components.
The inventors of the present invention have determined that known systems are unable to provide effective testing for vehicles that include active controls, since they fail to take full account of the control signals and their interaction with other components within the vehicle.